Add parentheses to the tokenizer and IsNumber() method

.gitignore

@@ -13,3 +13,4 @@
 
 # Dependency directories (remove the comment below to include it)
 # vendor/
+.idea

main.go

@@ -1,5 +1,8 @@
 package main
 
-func main() {
+import "./tokenizer"
 
+func main() {
+	example := "TÄRNÖ BEHÅLLAREThis message will be printedBEHÅLLARE"
+	tokenizer.Tokenize(example)
 }

tokenizer/check.go

@@ -0,0 +1,10 @@
+package tokenizer
+
+import "regexp"
+
+// IsNumber checks if the given character is a number and returns the condition
+func IsNumber(character string) bool {
+	numberRegex := regexp.MustCompile(`\d`)
+
+	return numberRegex.Match([]byte(character))
+}

tokenizer/check_test.go

@@ -0,0 +1,13 @@
+package tokenizer
+
+import (
+	"testing"
+)
+
+func TestIsNumber(t *testing.T) {
+	number := "1"
+
+	if !IsNumber(number) {
+		t.Errorf("IsNumber() failed.")
+	}
+}

tokenizer/tokenizer.go

@@ -6,9 +6,39 @@ type Token struct {
 	Value string
 }
 
+const (
+	LeftParentheses  = "("
+	RightParentheses = ")"
+
+	Space = " "
+)
+
 // Tokenize takes the given code, tokenize it and returns an array of Tokens
 func Tokenize(code string) (tokens []Token) {
 	var currentIndex int
 
+	// Iterate each character of the code
+	for currentIndex < len(code) {
+		character := string(code[currentIndex])
+
+		// Add parentheses tokens
+		if character == LeftParentheses || character == RightParentheses {
+			tokens = append(tokens, Token{
+				Type:  "PARENTHESES",
+				Value: character,
+			})
+
+			currentIndex++
+			continue
+		}
+
+		// Skip the spaces
+		if character == Space {
+			currentIndex++
+			continue
+		}
+	}
+
 	return
 }
+